全文获取类型
收费全文 | 332531篇 |
免费 | 3448篇 |
国内免费 | 950篇 |
专业分类
化学 | 167002篇 |
晶体学 | 5402篇 |
力学 | 15579篇 |
综合类 | 7篇 |
数学 | 38771篇 |
物理学 | 110168篇 |
出版年
2021年 | 3169篇 |
2020年 | 3389篇 |
2019年 | 3816篇 |
2018年 | 5237篇 |
2017年 | 5473篇 |
2016年 | 7434篇 |
2015年 | 4205篇 |
2014年 | 7100篇 |
2013年 | 16027篇 |
2012年 | 12600篇 |
2011年 | 15122篇 |
2010年 | 11134篇 |
2009年 | 11015篇 |
2008年 | 13452篇 |
2007年 | 13456篇 |
2006年 | 12348篇 |
2005年 | 10742篇 |
2004年 | 10034篇 |
2003年 | 8837篇 |
2002年 | 8823篇 |
2001年 | 10431篇 |
2000年 | 7695篇 |
1999年 | 5983篇 |
1998年 | 4988篇 |
1997年 | 4821篇 |
1996年 | 4508篇 |
1995年 | 3878篇 |
1994年 | 3826篇 |
1993年 | 3716篇 |
1992年 | 4102篇 |
1991年 | 4310篇 |
1990年 | 4102篇 |
1989年 | 4009篇 |
1988年 | 3788篇 |
1987年 | 3924篇 |
1986年 | 3689篇 |
1985年 | 4632篇 |
1984年 | 4686篇 |
1983年 | 3886篇 |
1982年 | 3977篇 |
1981年 | 3699篇 |
1980年 | 3650篇 |
1979年 | 3914篇 |
1978年 | 3907篇 |
1977年 | 3910篇 |
1976年 | 3881篇 |
1975年 | 3677篇 |
1974年 | 3616篇 |
1973年 | 3651篇 |
1972年 | 2606篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
The characterization of the clusters formed on alkaline hydrolysis of [PdCl4]2– was performed using17O,23Na,35Cl,133Cs NMR and UV spectroscopy. The chemical composition of the clusters was found to be [Pd(OH)2]
n
·nNaCl. No mononuclear oxo- or hydroxocomplexes were detected. The spatial structure of the clusters is stabilized by alkali metal cations.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 675–679, April, 1993. 相似文献
92.
93.
We consider tilde-geometries (orT-geometries), which are geometries belonging to diagrams of the following shape: Here the rightmost edge stands for the famous triple cover of the classical generalized quadrangle related to the group Sp4(2). The automorphism group of the cover is the nonsplit extension 3·Sp4(2) – 3 ·S
6. Five examples of flag-transitiveT-geometries were known. These are rank 3 geometries related to the groupsM
24 (the Mathieu group),He (the Held group) and and 37·Sp6(2) (a nonsplit extension); a rank 4 geometry related to the Conway groupCo
1 and a rank 5 geometry related to the Fischer-Griess Monster groupF
1. In the present paper we construct an infinite family of flag-transitiveT-geometries and prove that all the new geometries are simply connected. The automorphism group of the rankn geometry in the family is a nonsplit extension of a 3-group by the symplectic group Sp2n
(2). The rank of the 3-group is equal to the number of 2-dimensional subspaces in ann-dimensional vector space over GF(2). 相似文献
94.
95.
The simple relation between representations of the covering groups of SL2 and GL2 makes it possible to fuse and extend the recent metaplectic results of Shimura, Waldspurger, Flicker, and ourselves. By giving a new (purely local andL-function theoretic) treatment of the Waldspurger-Shintani correspondence, we also simplify some of Waldspurger’s original results. 相似文献
96.
97.
98.
We consider the growth of a spherical crystal in a supersaturatedsolution. In the first part, existence and uniqueness resultsfor radially symmetric growth are obtained, provided that thesupersaturation is not too large; conversely, when the far-fieldsupersaturation exceeds a critical value, it is shown that theradially symmetric solution ceases to exist in finite time.In the second part, we examine the linear stability of a radiallysymmetric similarity solution (in which the radius grows ast?) to shape perturbations. The results are compared with previousquasi-static analyses, and, in particular, the critical radiusat which the crystal becomes unstable is found to be largerfor small supersaturations, but smaller for large supersaturations,than those predicted by the quasi-static analysis 相似文献
99.
100.
A convenient method is proposed for the synthesis of all the individual methyl ethers of methyl 2-acetamido-2-deoxy-α-D-glucopyranoside based on the partial methylation of 2-acetamido-2-deoxy-α-D-glucopyranoside with dimethyl sulfate in an alkaline medium followed by preparative liquid column chromatography on silica gel of the resulting mixture of methyl ethers. 相似文献